Hyundai Repair: 2000 Hyundai Elantra overheating & Smoking, radiator hoses, hyundai elantra

Question
My 2000 Hyundai elantra is smoking and overheating.(94,000miles) It has done  this twice when I was on a high speed express road. The smoke is coming through the air conditioning vents and the cars needle shoots to the top, the check engine light comes on  then the car turns off. I have had the fan motor replaced. And a few other minor things. But It still does the same thing. After sitting for and hour or two the car will start again. But I  need to know what is the cause of this or what I should expect to pay to have this fixed. I am a single mother and I need a reliable car, and can't afford to spend a ton of money on repairs.

Answer
You'll need to check your cooling system to see what the issue is.

First, check the coolant level.  If it's low, check for leaks.

Once any leak or coolant level issues are resolved, then take the radiator cap off (cool engine) and start the engine.  As the engine warms, the coolant should begin to circulate.  If the fan starts or the coolant begins to boil out prior to the coolant circulating, the thermostat is probably not opening.  If you have trouble seeing whether the coolant is circulating by looking in the radiator filler neck, you can feel the radiator hoses.  If one hose is cool compared to the other, the coolant is not circulating.  If the coolant is circulating, they'll both be hot.

Once the coolant begins circulating, the fans should cycle on and off.  If the coolant begins boiling out prior to the fans cycling, you probably have an issue with the fan control circuit.  Since you've replaced the fan motor, it's probably safe to assume that it's good.

I'm a little concerned, though, that you drive the car until it stops running.  Overheating the vehicle this badly can damage the engine and radiator.  It's possible that you're continuing to have overheating problems now because of this.  One possibility is that the radiator's plastic tanks have begun to melt and have clogged the radiator passage.  Another is that the cylinder head has warped or you've damaged the head gasket to the point that it leaks.